Soak the salt cod in cold water in the refrigerator for 24 hours, changing the water 3 times. Drain well.

To make the pasta: In the work bowl of a food processor fitted with
a metal blade, add flour, 1 egg yolk and 1 tsp salt. Process with just
enough water to pull the dough together (1 or 2 Tbsp). Add chives, and
pulse 3-4 times to incorporate in the dough. Finish the dough on the
countertop, kneading in enough flour so the dough doesn’t stick to your
hands. Roll through a pasta machine following the instructions that
come with your machine, or roll as thin as possible with a rolling pin,
into 2 pieces, each 2 feet long. Cut the pasta into 16 pieces,
approximately 4 inches square, and set aside to dry while you make the
filling.

Preheat oven to 375°F. In a large bowl, mash together the salt cod,
potatoes and 1 whole egg. Season with pepper. Place a heaping
tablespoon of cod mixture on one end of each piece of pasta, and roll,
pinching in the ends as you go, to make the cannelloni. Place
cannelloni in a lightly oiled pan, seam side down, and bake 25 minutes.

In the meantime, make the sauce: In a sauce pan whisk together cream
and 3 egg yolks. Reduce by one-third over high heat. Add salt and
pepper to taste. Stir in sage, and continue cooking until the sauce is
reduced by half (should take 10-12 minutes in total). When the
cannelloni comes out of the oven, toss asiago cheese and marinara sauce
into the cream sauce, and stir to combine. Pour immediately over the
cannelloni, and serve hot.